Breve introducción a Blockchain

1. BLOCKCHAIN INTRO
OCTUBRE 2017

2. ➔ Separate ledgers => dependent on
individual entities / sources of trust
➔ Intermediaries and reconciliations
➔ Off-ledger messages
➔ Batches
BLOCKCHAIN IS A SHARED LEDGER
TODAY’S WORLD BLOCKCHAIN
➔ Single, shared ledger => single version of
truth
➔ Trustless
➔ Hyper-replicated => resilient and
immutable, yet cheap
➔ In real time

3. BLOCKCHAIN IS TRUSTLESS
➔ Anybody can generate
public / private key pairs
➔ Anybody can check
signatures
➔ The community
collectively audits
transactions and accepts
them into the ledger
LEDGER INITIAL NEW TRANSACTION
LEDGER FINAL
Public key Amount
Public key Amount
Public key 1 Amount1
Public key 2 Amount2
… …
private
key 1

4. SMART CONTRACTS ARE PROGRAMS
(AND DATA) ON THE SHARED LEDGER
A smart contract-
enabled blockchain
(e.g. Ethereum) is a
shared computing
platform where
transactions are:
➔ Notarized
➔ Immutable
➔ Real time
CRYPTOCURRENCIES
(E.G.BITCOIN)
SMART CONTRACTS
(E.G.ETHEREUM)
Public key Amount
Public key Amount
Public key Amount
Public key Amount
… …
➔ The ledger stores amounts of
cryptocurrency
➔ (Very simple) rules can be
attached to ledger entries
contract cryptobank {
mapping(address => uint) public balance;
function transfer(uint amount, address
receiver)
if(balance[msg.sender] >= amount) {
balance[msg.sender] -= amount;
balance[receiver] += amount;
} else {
throw;
}
}
...
➔ The ledger stores programs and data
➔ Programs are Turing-complete (i.e. general purpose)
➔ Data in smart contracts can represent anything
➔ Smart contracts can interact with other smart contracts
➔ Cryptocurrencies can also be supported – and used to pay
for shared computing power / notarization

5. ➔ ”Real” (fiat) money stays in an
omnibus account in the bank
➔ Easy integration through web
services
TOKENIZATION MAKES BLOCKCHAIN USEFUL
IN THE REAL WORLD
➔ Tokenizer deployed within
bank’s data center (no
external API calls needed)
➔ Client digital balances issued
on a smart contract, backed 1:1
with funds in the omnibus
account
… and now money is digital and
globally interoperable (through
other smart contracts!)➔ Anything (besides money) can be tokenized!!

6. PERMISSIONED BLOCKCHAINS: A PRAGMATIC
STEP FOR ENTERPRISES
➔ Not dependent on individual sources of
trust, but on a trusted set of validators =>
Not 100% trustless, but good enough
➔ Private – only nodes permissioned by the
validators can participate
➔ Simple consensus algorithms can be
used (instead of proof of work)
➔ Much more scalable and performant
➔ Needs to implement governance
mechanism
➔ … but needs to implement governance
mechanisms

7. PRIVACY IS PARAMOUNT
➔ Private smart contracts
are implemented as “sub-
blockchains”
➔ Payloads only stored in
participating nodes
➔ Private transactions
notarized anyway by the
(common) underlying
blockchain

8. BARCELONA, OCTUBRE 2017